docs: def get_mean_and_stddevs(self, sites, rup, dists, imt, stddev_types):
          """
          See :meth:`superclass method
          <.base.GroundShakingIntensityModel.get_mean_and_stddevs>`
          for spec of input and result values.
          """
          # extracting dictionary of coefficients specific to required
          # intensity measure type.
          C = self.COEFFS[imt]
          # Implements mean model (equation 12)
          mean = (self._compute_magnitude(rup, C) +
                  self._compute_distance(dists, C) +
                  self._get_site_amplification(sites, rup, C) +
                  self._get_mechanism(rup, C))
  
          stddevs = self._get_stddevs(rup, np.exp(mean), stddev_types, sites)
  
          return mean, stddevs